const byte LED_PIN = 9;
const byte KNOB_PIN = A0;

void setup() {
  pinMode(LED_PIN, OUTPUT);
  Serial.begin(115200);
}

void loop() {
  int value = analogRead(KNOB_PIN);
  int pwm = map(value, 0, 1023, 0, 255);
  analogWrite(LED_PIN, pwm);
  Serial.print("PWM: ");
  Serial.println(pwm);
  delay(100);
}